1. Field of the Invention
The present invention pertains to valves. In particular it is directed to valve assemblies for fluid valves. More specifically, it pertains to valve assemblies suitable for use with valves of the pressure or flow regulated type.
2. Description of the Prior Art
Most valves comprise a valve body having an inlet and outlet connected through a passageway which is normally provided with a seat and closure element. When the closure element is engaged with the seat, flow is prevented through the valve. When the closure element is unseated, flow is permitted. Most valve assemblies are normally made up of flat, conical or spherical poppet and seat combinations. Such assemblies inherently present surfaces which result in unbalanced forces on the assembly when fluid is flowing through the valve.
In an effort to overcome the inherent unbalanced pressure forces in ordinary valve assemblies, other approaches have been taken, e.g., curtain-flap valving units and piston metering valving units. Curtain-flap valving units are suitable for operation only at low pressures due to the tendency of the curtain flap material to extrude through the metering orifices. Piston metering valving units do not provide positive seals and low leakage is difficult to achieve.